Method and apparatus for rolling strip



March 6, 1945. R. J. WEAN METHOD AND APPARATUS FORROLLING STRIP ,/M NN MVzw PatentedvMar. 6, I

uNlIEo STATES PATEN'I OFFICE 'METHOD ANn aiignrsusroanomiuo a. RaymondJ. Wean, ,Wacrem 0hio, Vassigner Ato -The Wean Engineering Gompany,Inc., Warren, Ollio, a corporation o! Ohio A Application April 28, 1944,Serial No. 533,155

This invention relates to the rolling of metal strip and, in particular,to the cold reduction of strip bypassing it through a plurality of rollstands successively.

Metal strip is commonly reducedto' nal gauge -by cold rolling itprogressively in a plurality of 4-high mills or by repeated passes backand forth through a single stand reversing 4-high mill. Tension isusually applied. to the strip as it emerges lfrom the rolls and backtension may also be applied to the strip asl it enters the rolls.. Thedeformation of the material thus accomplished results from the combinedeffect of the tension stand of rolls 'and the other side or surface isdeformed to an extent greater than the rstmentioned side in passingthrough a succeeding stand of rolls. I employ a plurality of 3-high rollstands, eaohof which has a middle roll smaller in diameter than theouter rolls. AThe -strip .is

entered between the rollsso that in the first pass, one side of thestrip engages the middlel roll and, in the next pass, the other side ofthe strip engages the middle roll. I also maintain tensionon the stripentering and leavin'g'the mill. By this.method,.I work 'the two sides orsurfaces f sclaims. (ci. :so-3s) Journaled therein'.- The rolls of theseveral stands have their axes substantially in the same vertical-plane.I also provide strip-tensioning means and a coiler on each side of themill. By this arrangement, the strip may -be passed back and forththrough the mill successively until it has been rGeduced to the desirednal gauge.

Further novel features and advantages ofthe invention willbecomeapparent during the following complete description and explanationwhich refer to the accompanying drawing illustrating the apparatus andprocedure of a preferred .embodiment and practice. In the drawing,

Figure 1 is a central verticalA section thi-pugna mill and associatedapparatus. adapted for carrying out the method of my invention; l

Figure 2 is a sectional view to enlarged scale, through a piece of stripillustrating the reduction produced by passing it through the iirst 3^-high roll stand; and

'Figure 3 is a similar view illustrating the reduction effected o npassing the strip throughthe second stand.

Referring in detail to the drawing, a rolling mill. I0, as illustratedtherein, comprises spaced housings II, each having a window I2 adaptedto receive bearing .chucks in which are .iournaled the rolls of at leasttwo 3high roll stands. One

S-high stand of rolls includes outer rolls I3 and I4 and a middle rollI5. Another stand includes outer rolls I6 and II and a middle roll I8.The

ofthe strip' alternately and obtain a somewhat angular flow of the metalwhich results in what I elect to designate angular 11e-orientation. Theproduct of this method, when tested parallel and transverse to thedirection lof rolling, ex-

hibits characteristics more nearly equal than the product ofconventional rolling methods.

My invention alsohas a specialapplication to the removal of set which isthe transverse curvature Vsometimes exhibited 'by cold-rolled withtheconcave side 'of the strip in contact Worm wheels disposedv in cases 24and threaded I on thescrevvs- The chucks of the rolls forming thev upperstand are heldin proper relation by screws 25 actuated bymechanismindicated at 2B, similar to that just described.

The middle 'rolls I5 and Il! of the two B-high stands are quite s al1compared to the outer .,rolls.' In the illus rated. embodiment,"fr.eicwith the 'smallmiddle v roll whereby that side is deformed more thanthe otherside, thus-leaving the strip'V in' a nal shape which is morenearly level, I

The apparatus whichl prefer to employ includes a mill comprising a vpairof spaced -housings having a plurlityfof'-hgh roll stands ample.' the-middle rolls have a diameter about one-halfthat of the outer rolls.Whileth'e ratioof the diameters/of the l.middle and outer rolls need notfall within any speciiic limits,v the middle roll should have a diameterwhich is small conipared [to that of the outer rolls .or,' at least.to',

` l5 theAv diameter vof the outer .roll with which-the the iirst stand.Asclearly shown Y stripiseiected principally strip is in contact. Whileit is not necessary that the outer rolls of the stands be of the samediameter, this is usuallyconvenient from the operatnaled in spacedhousings 32. 'I'he rolls are preferably'arranged to be driven by anysuitable means and are also provided with means for applying brakingaction. The driving and braking may conveniently be combined byproviding an electric motor for driving the rolls and utilizingregenerative braking. The coilers 29 and 30 are likewise provided withsuitable driving motors and braking means. l

In utilizing the apparatus described above for rolling strip accordingto the method of my invention, I take-the outer end of a coil of strip33 disposed, for example, on the mandrel 36 of coiler 29 and pass itaround the lower roll 3i ofA tension stand 27, thence between the rollsof said stand and around the upper roll thereof. I then thread theleading end of the strip betweenthe rolls I3 and I5, thence around theroll I3, b E- tween it and the roll I6 and thence around the latter andbetween it and the roll I8. I then lead the strip around the upper rollof tension stand 28, .between the two rolls thereof and around thebottom roll, and thence to the mandrel of coiler 39.

with the screws 2s and 25 Oadjusted to give the desired drafts onthe-strip as it passes between the rolls of the two 3-highstandssuccessively, I drive the coiler 30 and the tension rolls 23. The coiler33, now serving as an uncoiler, and the rolls of tension stand 27 areretarded to provide the desired tension on the strip entering the irstor lowerstand of reducing rolls.

'Ihe rolls of the two 3high stands are preferablydriven by any suitablemeans, conveniently by -separate motor drives with speed-controlmeans sothat the rolls of the second stand may be driven at a peripheralspeedsuilciently greatv er than that of the rolls of the rst stand soas, to

maintain tension on the strip between'the two and anvil, the small rollperforming the function of the hammer and the large roll that of theanvil.

eiected. The alternate deformation of the two sides or surfaces of thestrip causes angular plastic iiow of the metal resulting in. angularre-y orientation of the grains. This tends t0 prevent thel occurrence ofpreferred orientation to a marked extent, leaving thematerial with morenearly uniform apparatus. The method of ,my invention apparently resultsin an angularv displacement oi lsuccessive layers of the originalmaterial caused by working each of the two surfaces successively to agreater extent than the opposite surface.v

Thedirection of relative slippage between the several planes is reversedin passing through the two stands successively.

After substantially the full length of the strip in the coil has beenvpassed through the two 40 tension on thestrip between` the stands. ystrip is again reduced by successive deformations f stands, despite theelongation resulting from the reduction in the rst stand. The tensionstand 28 and the coiler 30 maintain lforward tension on the stripemerging from the second stand.

It will he noted that, under th conditions de` scribed, the bottom sideor surface of the strip designated S will be engaged by the small or-`middle roll 'of the first stand, while the upper. .side or surface'ofthe strip will be engaged by the "middle roll of the second stand. Thiscauses the Y two'sidesor surfaces of the strip tobe deformed alternatelyor,v at least, causes one surface to be deformed much more lthan theother, in `each of the two passes. l diameters of the rolls engaging thestrip in each of the twopasses.

Figure 2 illustrates reduction of the strip effected on passing throughniFigure 2,

This results from the relative stands, the mill is reversed, as' Well asthe func-- tions of the tension stands and the coilers.' The A strip isthen 'subjected to a second pass through the two stands successivelyunder tension as described before. It will be evident that the rolls ofthe lower stand must be driven, on the reverse pass, at a speed higherthan that vof the rolls of the upper stand, in order to maintain thedesired eiectedfprincipally inthe two sides thereof .as previouslydescribed. Rolling ofthe strip in opposite directions is continued untilit has been reduced to the desired iinal gauge.

My invention also contemplates subjecting cold-rolled strip tovone ormore passes through a single stand of rolls to remove set,therei`rom.v

This set is a transverse curvature which sometimescharacterizesold-rolled material. To remove it, "I pass the stripbetween the lupper'roll I3 and the middle roll I5 of the Alower stand,as indicated by a chain line 35, or between the lower roll I6 and themiddle roll I8F ofthe upper stand, as indicated by chain line 36,depending on the direction of the set.. The strip should be startedthrough the mill so that the concave surface will be engaged by thesmall roll and thereby subieoted'to greater'deformation than the othersurface, in accordance with the explanationgiven above. A This tends toremove the curvature and e deliver the rstrip ina-shape more nearlyapproachonan enlarged scale theA the reductionA in the originalthickness of Izhef I I in the portion o1 the strip `thickness 'belowrthemedian plane between -the upper and lower surfaces. In other words,

the twosides of the 'strip are deformed along the curvature ofthe rollsI3 and I5, the deformationcurves being designateda andV lia. The of therolls, because of their dierent diameters; to be analogous to theactionof a hammerP ing a ilat or level condition. f Usually a.relatively 1 lightreductio in a single pass will sufce to re- Ise .,l

' It wlllbe apparent from the foregoing explana- Y tion that myinvention is characterized -bye nu" merous advantages. The .mostimportant has already been mentioned, vizwthe ,production of materialhaving more o1; lessvvunifo'rm characters istics `parallel'andtransverse to-the 4rolling direction. The preferred embodiment oftheapparatus, includingtwo 3-high roll stands in the vsaine housings, -isobviously capable of producing a much greater reduction; `than a single4-high Figure 3' illustrates the reductioneiected inl characteristicsparallel andv transverse to the direction of rolling than in the v caseof strip rolled by conventional methods and The.

roll stand. Two mills, suchv as that shown in Figure l, for example,will eiect areduction equivastrip, it mayA also `bes'utiliz'ed wfortemper rolling material such as tinplate stock while still in stripform. .v

A furtheradvantage of` the invention is that the strip is wrapped aroundone of the larger outer rolls of each stanji throughV an angle of morethan 180?, which results in a frictional grip on the material whereby itmay be subjected to' substantial tensions without slippage. j

^ Although vI have illustrated and described but:- a preferredembodiment and practice of the in` vention, it willoe recognized thatchanges in the construction and procedure disclosed may be made y'middle roll of one stand and the outer roll therey 2. In a method offlattening cold-rolled strip having a "set" or transverse curvature, thesteps including cold-rolling the strip and deforming the concave surfacethereof more deeply than theJ i convex surface.

3. In a method ofrolling strip, the steps including cold-reducing itprogressively in a plurality of 3-high roll stands disposed one abovethe otherQeach having a middle roll smaller than the outer rolls. andpassing the strip between the of adjacent the -other standthen betweenthe middle roll of the other stand and the outer roll without departingfrom the spirit of the invention I or the scope of the appended claims.-

I claim:- I 1. In a method of flattening cold-rolled strip having a. setor transverse curvature, the 'steps including cold-reducing the strip bypassing` it 'through a 3-high rolling mill having a middle roll smallerthan the outer rolls, and starting the strip through the mill so thatthe concave surface f thereof is engaged by the middle roll.

thereof nearer the first-mentioned stand.

. 4. The method dened by` claim 3 characterized by maintaining the stripin contact with^thex outer rolls engaged thereby throughout aboutof'their circumference. i

5. A mill for reducing strip comprising a pair of spaced housings havingwindows therein, two stands of three rolls' each having their necksposed in'said windows with their axes substatitially in verticalalinement, chucks slidable in said windws adapted .to receive saidnedks, and spacers between the chucks inwhich the necks of 0the tcm rollof the lower stand and the bottom roll of the upper stand are journaled,said speceri being movable relative to said housings with saiAlast-mentioned chucks.

a J' J. WEAN.

